DUBAI, UAE: Auction house Sotheby's Dubai will sell a black 555.55-carat diamond believed to be from outer space, known as "The Enigma," in London in February.

In an interview with FOX Business, Nikita Binani, jewelry specialist for Sotheby's and the head of sale for "The Enigma," said the diamond is expected to sell for between $4 million and $6.8 million, and the auction house will also be accepting cryptocurrency as a means of payment.

Black diamonds, also known as carbonado, are believed to be from outer space, because they are found closer to the Earth's surface than other diamonds and their chemical makeup, most notably the presence of a mineral called osbornite, which is "uniquely found in meteors," Binani said, as reported by Fox Business.

Black diamonds are only found in Brazil and Central Africa, but "The Enigma" is not just rare because of its origin, its journey has also been "exceptionally rare," Binani added, noting its current owner acquired it while it was still in its rough form, but it has been cut to 555.55 carats with exactly 55 sides, inspired by a Middle Eastern palm-shaped symbol called the Hamsa.

The diamond's size and cut also make it "extremely rare and unique," because most black diamonds this large are "almost always" in their rough form, she said, noting its has a high luster and brilliance, which is also rare for a black diamond, as they usually "feel opaque and sort of dull."

Before arriving in London in February for the auction, the diamond is touring Dubai and Los Angeles.